“What kind of magic is potentially stronger” is the “who would win” of the School of Necromancy world Everyone has several opinions on why their particular school of magic is superior to all the other ones. Necromancy can destroy/create life across the entire planet, Summoning can merge planes of existence, and Conjuration is literally the art of making the magical real, which you can imagine has quite a few large-scale applications. I mention in one of the things you can read up on Illusion that the illusions you create don’t have to be limited to things that can actually happen; it’s implied that this isn’t a feature of Illusion alone, that with the right process (which nobody knows but naturally everyone is looking into it) godlike power could be anyone’s for the taking.
Even Enchanting and Alchemy, while generally not being considered to stack up to the other schools, have enormous advantages in that anyone can do them.
Something not covered in Summoning class yet is that you can only banish something that was actually summoned in the first place. The Endless in the war are here thanks to wild magic and their own efforts, and as such just running around spamming the banishment axiom doesn’t help much